1. Field of the Invention
The present invention relates to a machine tool in which a spindle with a tool attached thereto is supported to be relatively movable in X-axis, Y-axis, and Z-axis directions, and more particularly, to a structure of a machine tool capable of machining a wide and long workpiece efficiently.
2. Description of the Related Art
As a gantry-type machining center for machining a relatively long workpiece, there is one described in, for example, Japanese Patent Application Laid-open No. 2001-219325 (patent document 1) or Japanese Patent Application Laid-open No. Hei 8-150534 (patent document 2). The one described in the patent document 1 is structured such that a gate-shaped column 7 is disposed on a long bed 2 to be movable in an X-axis direction, a saddle 25 is disposed on a front face of a cross rail 7c of a column 7 to be movable in a Y-axis direction, a ram 30 is disposed on the saddle 25 to be movable in a Z-axis direction, and a spindle 31 with a tool 32 attached thereto is disposed on the ram 30.
In a machining center of this type, a relatively long workpiece W is placed on the bed 2, and then the column 7, the saddle 25, and the ram 30 are relatively moved in the X-axis, Y-axis, and Z-axis directions respectively, and whereby the spindle 31 applies predetermined machining to the workpiece W.